Exogenous insulin therapy slows weight loss in type 2 diabetic patients.

The impact of exogenous insulin therapy on the ability of obese, noninsulin dependent diabetic patients to lose weight was studied. Weight loss data from seven insulin-requiring type 2 diabetic patients, 11 sulfonylurea-treated type 2 diabetic patients and 12 non-diabetic controls on very-low-calorie diets were analyzed. Upon starting the diet, insulin doses were reduced by 50 percent and given once daily as intermediate-acting insulin. Doses were adjusted to maintain capillary blood glucoses between 6.7 and 10 mM. Sulfonylureas were stopped upon initiation of the diet. Patients were seen weekly for determination of their dietary compliance, medical status, glucose control, activity level and amount of weight loss. The insulin-treated subjects lost significantly less weight per week, whether expressed as kilograms, change in body mass index or percent of initial body weight lost. Treatment of obese type 2 diabetic patients with insulin retards their ability to lose weight independent of caloric intake.